Collapsible dispensing containers are widely used for packaging pharmaceutical products, dentifrice, cosmetics, toiletries and the like. In the past, such containers were made of plastic or metallic materials. However, as mentioned in U.S. Pat. No. 3,260,410 issued on July 12, 1966 to Brandt et al and U.S. Pat. No. 3,347,419 issued on Oct. 17, 1967 to Brandt et al, the plastic containers and the metallic containers which were used in the past had inherent drawbacks. For example, metal containers are costly to produce and often require a protective interior coating in order to protect the metal from attack by the acidic or alkaline contents of the containers. Plastic containers, on the other hand, are relatively inert but permeable, in varying degrees, to moisture, essential oils and other volatile ingredients. In addition, many of the plastics which are suitable for making the containers are permeable to oxygen.
In recent years, collapsible dispensing containers have been made of multiply plastic laminate structures which include an intermediate layer of a metal foil, e.g., aluminum foil. Typically as described in the aforementioned U.S. Pat. No. 3,347,419 of Brandt et al, such laminate structure have an inner layer of a thermosplastic material which forms the interior surface of the container. This inner layer is adhesively bonded to the foil layer by a suitable adhesive material that prevents delamination of the layers due to product attack. The outer surface of the foil layer is coated with a protective layer and a decorative layer is usually applied to the protective layer for aesthetic purposes.
The inclusion of a metal foil layer in the laminate structure used in making dispensing tubes or containers has several disadvantages. Metal foils are costly and more expensive than the plastic materials usually used in making such tubes. Their elimination or replacement with a less expensive substitute, therefore, decreases the cost per unit of container. In addition, and significantly, the inclusion of an intermediate layer of metal foil in the laminate structure complicates the manufacturing process, and slows down the rate of production of such tubes. Thus, and with the advent of high speed machinery and equipment for making collapsible dispensing containers, the elimination of the metal foil layer, or its substitution by a suitable plastic layer, permits construction of the containers more rapidly and at lower cost.
While an all-plastic laminate structure offers cost advantage and is less complicated to fabricate into collapsible tubes than metal foil-containing laminates, not all of the plastic materials have been found to be well suited for making such tubes. The reason is that while metal foil-containing laminate structures exhibit good crease-retention properties, most plastic materials used for making collapsible dispensing tubes exhibit poor crease-retention. This crease-retention ability or so-called "dead fold" property of the laminate structure is a significant consideration.
Accordingly, it is an object of the present invention to provide a laminate structure for making collapsible containers, wherein the laminate structure does not include a metal foil layer.
It is a further object of this invention to provide an all-plastic laminate structure for collapsible dispensing tubes wherein the laminate structure exhibits satisfactory and acceptable crease-retention and dead fold characteristics.
It is also an object of this invention to provide an all laminate structure which permits the dispensing containers to be made at higher rates and less expensively than metal foil-containing laminate structure.
The foregoing and other objects and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.